Gentlefolk,
I am part of a group of fellow Amateurs who have been working on
homebrew phasing Direct Conversion Tranceivers for a while now.
Details of our first attempt can be found at: -
www.stevef.demon.co.uk/qrp2k/qrp2000home.htm
and the later iteration is at
http://www.qrp2001.freeserve.co.uk/background.htm .
Design and prototyping for the QRP2004 is well underway and will be
published when we can get round to it. These are homebrew designs, the sad
thing is that we were trying to get someone with more time that we have to
kit them however there was little interest at the time we presented the
QRP2000 at Dayton. I think we have all built, or in my case are building K2s
as well. There is something about the clarity of the audio from a DC RX
which superhets never manage to achieve. The first ham project I ever made
was a Sudden DCRX uring the venerable NE602...I had a lot of fun with
it....and was hooked....
Bye for now,
Steve
----- Original Message -----
From: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: "Elecraft Discussion List" <elecraft@mailman.qth.net>
Sent: Tuesday, March 15, 2005 9:43 AM
Subject: Re: [Elecraft] rcvr designs prc-2000 USES DIRECT CONVERSION!
Another example is the Collins 95S-1A produced some years ago. This
receiver
is 'Software Driven' and covers the range from 5 kilohertz to 2 GHz in
steps
down to 1Hz. Its architecture is hybrid. Antenna signals between 5 kHz and
30 MHz are upconverted to 51.2 MHz and directly converted from there to
baseband - e.g. audio. Antenna signals between 20 MHz and 2 GHz are
Directly Converted to baseband, and yes there is an overlap between 20 MHz
and 30 MHz. Baseband signals are processed by DSP. Modes handled are CW,
L.SB, U.SB, I.SB, FM and AM.
IMHO Direct Conversion has great performance potential, and the techniques
in circuitry developed during the past decade could perhaps make Direct
Conversion the architecture of choice sometime in the future. There is no
doubt in my mind that SSB signals sound "better" from a DC receiver,
likewise CW.
73,
Geoff
GM4ESD
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <elecraft@mailman.qth.net>
Sent: Tuesday, March 15, 2005 3:41 AM
Subject: [Elecraft] rcvr designs prc-2000 USES DIRECT CONVERSION!
He would joke about my K2 manpack. His used PRC-2000 cost over $2000.
The receiver used. DIRECT CONVERSION. THEY DID FIND A WAY TO GET RID
OFALL
THE AUDIO ARTIFACTS AND IMAGES THAT WERE THE REASON WHY SUPERHET BET
DIRECT
CONVERSION AS THE GOLD STANDARDOF RCVRS.
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